Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

machoprogrammer:Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

machoprogrammer:Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

It's a hundred thousand light years side to side.It bulges in the middle, thirty thousand light years thick,But out by use it's just three thousand light years wide.We're thirty thousand light years from galactice central point,We go round every two hundred million years.And our galaxy is only one of millions and billions in this amazing and expanding universe.

doglover:Faster than light travel might be possible with a dyson sphere.

I've used one of those before. They're a bit pricy, but when you really need to get somewhere quick, or vacuum under the furniture, they can't be beat. Avoid their stupid circular fan thingies, they're loud and have horrible flow.

Why would a planet that has water also necessarily have a breathable oxygen atmosphere? That does not follow, as I understand it. Our own Earth had oceans for hundreds of millions if not billions of years before it finally got a breathable (by land animals) oxygen atmosphere. Molecular (O2 atmospheric oxygen mainly forms from a lot of blue-green algæ and other photosynthesizing plants performing photosynthesis, and this takes a very long time to make sufficient O2 for human survival.

Yes, there would need to be an atmosphere (for pressure) to enable liquid water, but it doesn't have to have significant O2 content.

For a planet to be habitable by humans, it would need not only oceans and an atmosphere with roughly ¹/5 O2 content and a gravitaitonal strength of ~1G (±¼G or so), but also a solid iron inner core inside a molten iron outer core to generate a sufficient magnetic field to produce a magnetosphere that can repel solar wind and cosmic radiation (for similar reasons, it cannot be in nor too near to the galactic core, as not even a magnetosphere considerably stronger than Earth's would suffice to repel radiation that would demolish DNA molecules). Of course, it would also need to be in the "goldilocks zone" of its star, but having oceans pretty much requires that, too.

For it to be capable of evolving complex land animals on its own that may well have achieved sapience and technology, it would need all of that (perhaps differing in the amount of oxygen and gravity) plusone moon with a mass that's a substantial fraction of the planet's own. Why? Because sea animals stay in the oceans unless there is evolutionary pressure to move to land, and that only happens in tidal pools (thus providing land that alternates between being underwater and being exposed, thus providing an evolutionary pressure for amphibians to evolve), which requires tides. Regular, predictable tides. No moon means no tides (or at least only wimpy solar tides barely worth mentioning), and multiple moons means tidal chaos, not regular predictable tides.

According to currently en vogue theory, Earth's own Moon is a complete fluke, having been knocked from the Earth itself by a massive collision early on, leaving an enormous crater in the Earth that we now call the Pacific Ocean.

What are the odds of such a thing having happened to some other planet reasonably near us, that also meets all of the other qualifications?

Pluto's getting a very close fly-by in 2015, oddly by the probe that took that awesome pic of the eruption on Europa a few years ago. New Horizons for the win...That Curiosity even landed is a testament to all those other sciences.

COMALite J:For it to be capable of evolving complex land animals on its own that may well have achieved sapience and technology, it would need all of that (perhaps differing in the amount of oxygen and gravity) plus one moon with a mass that's a substantial fraction of the planet's own. Why? Because sea animals stay in the oceans unless there is evolutionary pressure to move to land, and that only happens in tidal pools (thus providing land that alternates between being underwater and being exposed, thus providing an evolutionary pressure for amphibians to evolve), which requires tides. Regular, predictable tides. No moon means no tides (or at least only wimpy solar tides barely worth mentioning), and multiple moons means tidal chaos, not regular predictable tides.

You are assuming that things happen very much like on earth, which is a massive assumption. Even if you did, I don't see your moon hypothesis as very sound - if you assume plant like things in the sea, and animal like things eating them, then plants will have an advantage to migrate to land to avoid being eaten, so then there will be an advantage for animals to go onto land. No moon, tides, tidal pools or whatever required.

machoprogrammer:Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

Yeah, I'm wondering if they are actually referring to the several dwarf galaxies that orbit the milky way at about those distances (between 200 and 500 kly) And perhaps the journalist misinterpreted this as "stars" in the "outer reaches" of the the milky way.

Pluto's getting a very close fly-by in 2015, oddly by the probe that took that awesome pic of the eruption on Europa a few years ago. New Horizons for the win...That Curiosity even landed is a testament to all those other sciences.

I'm well aware of New Horizons, although it's "Pluto Express" in my head for some reason.

A flyby is not a mission. We can see Europa from earth with centuries old telescopes. Getting closer puctures is just more of a cock-tease. I want a plutonium tipped ice drill on a submersible probe with kilometers of cable to a broadcast unit on the surface beaming back to an oribtal relay that sends us pictures of alien fish or lack thereof. That's a mission.

And the Curiosity jet landing was nice. Sadly, thanks to the complete lack of showmanship over at NASA, it's just a geology probe. Great for astro-geologists, lamer than studying on prom night for everyone else.

COMALite J:Why would a planet that has water also necessarily have a breathable oxygen atmosphere?

Agreed. Free oxygen is highly reactive, and normally binds itself up in mineral oxides. It requires life to keep free oxygen floating around in our atmosphere. In other words, life (or at least some very interesting active chemistry) is probably a prerequisite for an oxygen atmosphere, not vice versa.

Why would a planet that has water also necessarily have a breathable oxygen atmosphere? That does not follow, as I understand it. Our own Earth had oceans for hundreds of millions if not billions of years before it finally got a breathable (by land animals) oxygen atmosphere. Molecular (O2 atmospheric oxygen mainly forms from a lot of blue-green algæ and other photosynthesizing plants performing photosynthesis, and this takes a very long time to make sufficient O2 for human survival.

Yes, there would need to be an atmosphere (for pressure) to enable liquid water, but it doesn't have to have significant O2 content.

For a planet to be habitable by humans, it would need not only oceans and an atmosphere with roughly ¹/5 O2 content and a gravitaitonal strength of ~1G (±¼G or so), but also a solid iron inner core inside a molten iron outer core to generate a sufficient magnetic field to produce a magnetosphere that can repel solar wind and cosmic radiation (for similar reasons, it cannot be in nor too near to the galactic core, as not even a magnetosphere considerably stronger than Earth's would suffice to repel radiation that would demolish DNA molecules). Of course, it would also need to be in the "goldilocks zone" of its star, but having oceans pretty much requires that, too.

For it to be capable of evolving complex land animals on its own that may well have achieved sapience and technology, it would need all of that (perhaps differing in the amount of oxygen and gravity) plus one moon with a mass that's a substantial fraction of the planet's own. Why? Because sea animals stay in the oceans unless there is evolutionary pressure to move to land, and that only happens in tidal pools (thus providing land that alternates between being underwater and being exposed, thus providing an evolutionary pressure for amphibians to evolve), which requires tides. Regular, predictable tides. No moon means no tides (or at least only wimpy solar tides barely worth mentioning), and multiple moons means tidal chaos, not regular predictable tides.

According to currently en vogue theory, Earth's own Moon is a complete fluke, having been knocked from the Earth itself by a massive collision early on, leaving an enormous crater in the Earth that we now call the Pacific Ocean.

What are the odds of such a thing having happened to some other planet reasonably near us, that also meets all of the other qualifications?

Sorry youse guise, I put the sarcasm on a bit thick. I was making a joke about how astronomy stories are full of may haves and perhapses, and then retracted a week later. Remember Zarmina? It's my favorite of these stories. It was described in great detail and even named after the discoverer's wife. Now no one's even sure it's really there.

machoprogrammer: Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

Wait, really?

(´･_･`)

I fear for kids today.

Yeah... But, outside of the structure of the galaxy is a group of stars in a "halo," held to the Milky Way by gravity, but NOT part of the structure. Thus:

GeneralJim:doglover: machoprogrammer: Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

Wait, really?

(´･_･`)

I fear for kids today.Yeah... But, outside of the structure of the galaxy is a group of stars in a "halo," held to the Milky Way by gravity, but NOT part of the structure. Thus:

Son of Thunder:"If we infer the properties of the stars that we think are reasonable, then we find the mass of the Milky Way could be half as massive as we currently believe," added Deason

But what if some of the stars are unreasonable?

Demanding top billing, a cut of the gross, flowers in their dressing room, sort of thing?

doglover:GeneralJim: doglover: machoprogrammer: Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

Wait, really?

(´･_･`)

I fear for kids today.Yeah... But, outside of the structure of the galaxy is a group of stars in a "halo," held to the Milky Way by gravity, but NOT part of the structure. Thus:

[www.astrobio.net image 400x399]

I was more worried that he couldn't tell radius and diameter apart.

You seem to have missed that, too.

A 100,000 ly diameter would mean a 50,000 ly radius, which is an order of magnitude smaller than the numbers quoted in the article, so his point stands.

What a horrible article. Big headline is Galaxy could be half as massive. Details have scientists saying "this could", "maybe after more observation", "a little surprised". The author is just cherry picking ideas and saying it is likely.

Astronomy is one of those sciences where everyone loves to hear about what is going on. We all love to see pretty pictures, find out about new planets, comets, really anything. Even dark matter and space time are interesting to almost everyone because it reminds them of Star Trek or other sci-fi things. But then there is the problem, most of astronomy is math and actually rather boring and slow to prove ideas. Big stories about certain discoveries actually tend to be not that important or the end result of decades of work but because it might appeal to the people it is made into a big deal.

So astronomers get stuck having to do real science but then dumbing it down to average intelligence levels which then gets misinterpreted by science writers. It's the reason all distances in science articles are in light years. Average people have some what of a grasp of that, but almost all astronomers use parsecs.

COMALite J:According to currently en vogue theory, Earth's own Moon is a complete fluke, having been knocked from the Earth itself by a massive collision early on, leaving an enormous crater in the Earth that we now call the Pacific Ocean.

Hm, no. The Earth was liquified by the collision. No crater was left behind.

Bondith:Son of Thunder: "If we infer the properties of the stars that we think are reasonable, then we find the mass of the Milky Way could be half as massive as we currently believe," added Deason

But what if some of the stars are unreasonable?

Demanding top billing, a cut of the gross, flowers in their dressing room, sort of thing?

doglover: GeneralJim: doglover: machoprogrammer: Stars in the far outer reaches of the Milky Way, between 260,000 and 490,000 light-years from the galactic center, are cruising around surprisingly slowly, researchers found. Galactic mass and star velocities are linked, so the results could have big implications.

I thought the galaxy was only 100,000 light years across? How does that work?

Wait, really?

(´･_･`)

I fear for kids today.Yeah... But, outside of the structure of the galaxy is a group of stars in a "halo," held to the Milky Way by gravity, but NOT part of the structure. Thus:

[www.astrobio.net image 400x399]

I was more worried that he couldn't tell radius and diameter apart.

You seem to have missed that, too.

A 100,000 ly diameter would mean a 50,000 ly radius, which is an order of magnitude smaller than the numbers quoted in the article, so his point stands.

You seem to have missed that.

No, no, no.

The radius is 5d.

2r= dr= 1/2dr don't like that shiat.r hits the gym, starts on the HGH.r=5dQED

COMALite J:For it to be capable of evolving complex land animals on its own that may well have achieved sapience and technology, it would need all of that (perhaps differing in the amount of oxygen and gravity) plus one moon with a mass that's a substantial fraction of the planet's own. Why? Because sea animals stay in the oceans unless there is evolutionary pressure to move to land, and that only happens in tidal pools

Bull Crap. (Its perfectly possible that being a double planet is very important (see Venus) but the idea that life wouldn't move onto land without tides is massively retarded -- swamps, rivers, lakes, ponds, anyone?)